Battaglin, W.A., and Goolsby, D.A.1994Estimates of nitrogen-fertilizer sales for the conterminous United States in 19911.0Series_Name WRIR-94
Issue_Identification 4176
Lakewood, COUSGShttp://water.usgs.gov/lookup/getspatial?nit91Battaglin, W. A.; Goolsby, D. A.1995Spatial data in geographic information system format on agricultural chemical use, land use, cropping practices in the United StatesreportU.S. Geological Survey Water Resources Investigative ReportWRIR 944176Reston, VAU.S. Geological Surveyhttp://pubs.er.usgs.gov/publication/wri944176This coverage contains estimates of nitrogen-fertilizer sales for the
conterminous United States in 1991 as reported by the U.S. Environmental
Protection Agency (1990) and by Jerald Fletcher (West Virginia University,
written commun., 1992). Nitrogen-fertilizer sales estimates in this
coverage are reported for each county polygon in tons of actual nutrient
sold (inorganic nitrogen, phosphate, and potash) as distinct from total
tons of fertilizer product.
The data are summarized for fertilizer years (i.e. the 1987 fertilizer
year runs from July 1, 1986 to June 30, 1987).
The polygons representing county boundaries in the conterminous United
States, as well as lakes, estuaries, and other nonland-area features were
derived from the Digital Line Graph (DLG) file representing the
1:2,000,000-scale map in the National Atlas of the United States (1970).
Nitrogen-fertilizer
Commercial fertilizer
Fertilizer use
Counties
United States
The nitrogen-fertilizer sales estimates in this coverage are intended
for use in estimating regional fertilizer sales, and in producing
visual displays and mapping relative rates of fertilizer sales across
broad regions of the United States.
Procedures_Used:
NITROGEN-FERTILIZER SALE ESTIMATES
An automated procedure was developed for processing the raw
fertilizer-sales estimates into ARC/INFO coverage attributes.
The procedure is summarized bellow:
1) copy raw data to file called nit.temp and edit off header records,
2) run script nitdat.sc making file called nit.in
3) edit nit.in removing extra column between state and county FIPS
codes, and extra lines at end of file ("00000" FIPS),
4) rename nit.in nit%year%.inp
5) copy county2m coverage to coverage called nit%year%
6) run nitadd.aml
COUNTY BOUNDARIES
This series of maps was published as part of the National Atlas of the
United States (U.S.Geological Survey, 1970). The maps for the conterminou
United States were digitized in 15 sheets and published in the Digital Lin
Graph (DLG) format as described by Domeratz and others (1983).
Each sheet was prepared by reading the DLG files of the political and
water bodies layers, converting them to ARC/INFO, extracting the county
boundaries and the coastline, respectively, and joining the two layers.
FIPS codes were assigned to all polygons by using available sources and
were checked manually.
Boundaries with adjacent sheets of the 15-sheet set were edgematched
manually, arbitrarily choosing one of the sheets as the "correct" border.
Edgematching operations adjusted the linework as far as was necessary so
that the coverages would fit to a tolerance of 100 meters. The coverage
(referred to herein as Version 1.0) was stored as 49 separate coverages
(48 States and the District of Columbia) because the ARC/INFO software in
use at the time could not process the entire coverage. Individual States
could be joined by specifying a tolerance of 100 meters.
From time to time, adjustments were made to the State coverages to
reflect changes in U.S. counties. It is believed the accuracy of
these adjustments is comparable to the original linework.
For Version 2.0, all State coverages were rejoined and manually edited
to produce a perfect edgematch between all States. For States on the
original map sheet boundaries, this adjustment averaged less than 20
meters and in no case was more than 100 meters. The whole coverage was
CLEANed to a tolerance of 20 meters, which resulted in few, if any, effect
on small offshore islands. The coverage also was checked to ensure that it
represented current U.S. counties or county equivalents.
The coverage in Version 1.0 stopped at the coastline.
There was no attempt to depict offshore areas. This created some problems
when the coverage was used to assign county codes to sampling stations
located near the coast. To help in this matter, Version 2.0 includes
offshore extensions of the county polygons. The (water) boundaries of
many of these polygons are arbitrary.
The Canadian Great Lakes features are another new addition to Version 2.
They were added to improve the utility of the coverage for visual displays
Although the Canadian Great Lakes are logically represented by a single
polygon, practical considerations -- the inability of some software to plo
polygons with a large number of vertices -- made it necessary to separate
them into four polygons. The dividing lines are located in narrow channel
to minimize interference with plotting patterns. Canadian islands within
the Great Lakes also were included.
All ticks were relocated to places that are easily visible on maps
of the United States, to help in registering maps that may not
otherwise have adequate registration information.
To expedite accessing parts of the coverage, certain items have
been indexed with the procedure, INDEX_COUNTY.AML. See Section 3
above. A spatial index also was created.
When using this coverage to clip or intersect other coverages, a
tolerance as low as 2 meters can be used.
The processing used to derive this coverage moved boundaries from their
positions on the original maps. In cases of conflicting lines, preference
was given to forming the correct topology. Strictly speaking, this coverag
is not identical to the source materials. These changes were unavoidable
in producing a continuous coverage of the conterminous United States.
Revisions:
COUNTY POLYGON DATA
Revision 1.0, 12/17/90. This revision represents numerous
corrections and minor modifications made to this set of coverages
from its construction in 1985 through the revision date.
Revision 2.0, 3/18/91. Major reworking of the coverage, combining
all State coverages.
Reviews_Applied_to_Data:
The fertilizer-sales data processing procedure and attribute data have
been peer reviewed in 1993 by Leonard Orzol and Barbara Ruddy, both
hydrologist with the USGS.
The county boundaries in this coverage have received no formal review.
They have, however, been used in numerous applications where serious error
would have been obvious. Some State coverages were corrected following
such use. The offshore polygon extensions and the Canadian Great Lakes
polygons have had no review.
Related_Spatial_and_Tabular_Data_Sets:
This coverage is part of series of 1:2,000,000-scale base maps
covering the United States. Layers in this set include:
COUNTY -- County boundaries.
STATE -- State boundaries (formed from COUNTY).
WATERBOD -- Water Bodies.
STREAM -- Streams.
HUC -- Hydrologic cataloging units (basins).
Other_References_Cited:
Domeratz, M. A., Hallam, C. A., Schmidt, W. E., and Calkins, H. W.,
1983, USGS Digital Cartographic Data Standards: Digital Line
Graphs from 1:2,000,000-scale Maps. U.S. Geological Survey
Circular 895-D, 38p.
Nebert, Douglas D., 1994, Design of the distributed spatial data library
for the Water Resources Division, U. S. Geological Survey: U. S.
Geological Survey Open-File Report, 94-327, 30 p.
U.S. Department of Commerce, 1989a, Census of agriculture, 1987 -- Final
county file: U.S. Department of Commerce, Bureau of the Census,
[machine-readable data file]
U.S. Department of Commerce, 1989b, Census of agriculture, 1987 -- Final
county file technical documentation: U.S. Department of Commerce,
Bureau of the Census, Data User Services Division.
U.S. Environmental Protection Agency, 1990, County-level fertilizer
sales data: U.S. Environmental Protection Agency, Office of Policy,
Planning, and Evaluation, PM-221.
U.S. Geological Survey, 1970, National atlas of the United States
of America: Washington D.C., U. S. Geological Survey, 417 p.
Notes:
DOCUMENTATION
The documentation for this coverage was generated by using the ARC
macro language (AML) program document.aml available from the U.S.
Geological Survey (Nebert, 1994).
1997The data are summarized for fertilizer years (i.e. the 1987 fertilizer
year runs from July 1, 1986 to June 30, 1987).
Complete(Several revisions noted)
Continually
Daily
Weekly
Monthly
Annually
Unknown
As Needed
Irregular
None planned
-128.07002717-65.2569837848.2619402722.67774911NoneNitrogen-fertilizer sales for counties in the United States, 1991inlandWatersNoneConterminous United StatesNoneNoneNoneNone(describe any restrictions or legal prerequisites for accessing
the data set. Put "None" if there are no restrictions)
NITROGEN-FERTILIZER SALES DATA
Estimates of nitrogen-fertilizer sales by county were generated by
the U.S. Environmental Protection Agency (1990) and by Jerald
Fletcher (West Virginia University, written commun., 1992) by using
the following procedure:
(1) compiling annual State fertilizer-sales data reported as tonnages to
the National Fertilizer and Environmental Research Center of the TVA;
(2) calculating the ratio of expenditures for commercial fertilizers by
county to expenditures for commercial fertilizers by States from
the 1987 Census of Agriculture (U.S. Department of Commerce, 1989a);
and
(3) computing annual county-level nitrogen-fertilizer sales, in tons, by
multiplying estimates of annual States sales by the ratio of county
expenditures to States expenditures.
In some counties no fertilizer sales were reported, but some fertilize
use was reported in the Census Data.
Although fertilizer expenditures estimates (in $1,000) represent
the 1987 growing year, the nitrogen-fertilizer sales estimates (tons)
generally reflect 1991 amounts.
Estimates of nitrogen-fertilizer sales by county were constructed from
a combination of data reported to State regulatory agencies and from
data in the 1987 Census of Agriculture. Fertilizer-sales data submitted
annually to State regulatory agencies by fertilizer dealers reflect
total sales without regard to the land use for which it was bought, or
the State (or county) in which the fertilizer was actually used. In
the Census of Agriculture sampling and statistics were used to account
for nonresponding farm operations (U.S. Department of Commerce, 1989b).
Thus, the information that describes county-level fertilizer sales is
subject to sampling variability as well as reporting and coverage
errors. Census disclosure rules also prevent the publication of
information that would reveal the operation of individual farms.
COUNTY BOUNDARIES
The original files for this map were provided in 15 sections. Boundaries
near the edges of sections have been adjusted in edgematching.
Polygons that extend into the water (an ocean or the Great Lakes) should
be considered arbitrary.
William A. BattaglinU.S. Geological Survey, Water Resources Div. (WRD)Hydrologist, Office of the Regional Hydrologistmailing addressP.O. Box 25046, Denver Federal Center, Bldg. 25LakewoodCO80225USA1-888-275-8747303-236-5959wbattagl@usgs.gov8:00am-4:30pm MSTPlease contact thru emailhttp://water.usgs.gov/GIS/browse/nit91.gifIlllustration of data setGIFNoneUnclassifiedNonedgux, 5.4R3.10, AViiON UNIX, ARC/INFO version 7.0.4U.S. Geological Survey, Water Resources Div. (WRD)Office of the Regional HydrologistEstimates of nitrogen-fertilizer sales for the conterminous United StatesLakewood, ColoradoP.O. Box 25046, Denver Federal CenterSee Entity_Attribute_InformationSee ExplanationAttribute accuracy is described, where present, with each
attribute defined in the Entity and Attribute Section.
Polygon and chain-node topology present.(Information in wordy narrative form describing omissions,
selection criteria, generalization, definitions used, and other
rules applied to derive the data set)
(An explanation of the accuracy of the horizontal coordinate
measurements and a description of tests used, if any, to
determine horizontal positional accuracy. This is different
from horizontal resolution as reported in the DOC file.
Positional accuracy defines how correctly the digital features
match real-world features and woiuld be related to the concept
of the National Map Accuracy Standard -- xx% of well-defined
point features fall within xx units of their true position.
The resolution is the smallest unit of measure the GIS can
reliably manage without truncation or rounding.)
approx. 1 kmResolution as reported(The same as above, but for vertical information that may
be encoded with the 2-D features such as cell or contour
estimates of a vertical dimension. A description of the
contour interval of input data and its basis could be described
here.)
Unspecified0000Unspecified2,000,000Unspecified0000UnspecifiedUnspecifiedUnspecifiedRESELECT COUNTY2M COUNTY.NEW POLYNone199111121528NoneLABELERRORS COUNTY.NEWNone199111121529NoneLABELERRORS COUNTY.NEWNone199111121556NoneEXTERNALALLNone199111121721NoneRENAME COUNTY.NEW COUNTY2MNone199111131249NoneCREATELABELS COUNTY2M 5000None199111151656NoneEXTERNALALLNone199112041410NoneCOPY COUNTY2M /ARC3/WORK/LIB/COUNTY2MNone199201020833NoneCOPY /ARC3/WORK/LIB/COUNTY2M COUNTY.AGNone199201021527NoneRENAME COUNTY.AG CNTY.AGNone199201021527NoneCOPY /ARC3/WORK/CNTY.AG COUNTY2MNone199201071423NoneEXPORT COVER COUNTY2M COUNTY2MNone199201171350NoneCOPY /ARC3/WORK/LIB/COUNTY2M COUNTY2MNone199201211549NoneBUILD COUNTY2M POLYNone199201211615NoneARCEDIT /ARC3/WORK/COUNTY2MNone199201220948NoneBUILD COUNTY2M POLYNone199201220956NoneIDEDIT COUNTY2M POLYNone199201221101NoneCOPY COUNTY2M /ARC3/WORK/LIB/COUNTY2MNone199201221102NoneIDEDIT COUNTY2M POLYNone199203301537NoneEXPORT COVER COUNTY2M COUNTY2MNone199206081103NoneARCEDIT /ARC3/WORK/LIB/COUNTY2MNone199208031748NoneBUILD COUNTY2M POLYNone199208031758NoneCLEAN COUNTY2M # 2 2 POLYNone199208031846NoneCOPY COUNTY2M /WB2/DB/USA/COUNTY2MNone199208040919NoneCOPY /WB2/DB/USA/COUNTY2M NIT91None199212171427NoneCOPY NIT91 /WB/AG/NITRATE/NIT91None199301200859NoneCOPY /WB/AG/NITRATE/NIT91 NIT91None199303221544NoneDOCUMENT NIT91 DELETE WBATTAGLNone199303221544NoneDOCUMENT NIT91 COPY /ARC3/EPA1/NIT/NIT86 WBATTAGLNone199303221545NoneDOCUMENT NIT91 UPDATE WBATTAGLNone199303221608NoneEXPORT COVER NIT91 NIT91None199304140920NoneEXPORT COVER NIT91 NIT91None199404251438NoneEXPORT COVER NIT91 NIT91None199408100954NoneCOPY /ARC3/EPA1/NIT/NIT91 NIT91None199412151517NonePROJECTDEFINE COVER NIT91None199412151526NoneDOCUMENT NIT91 UPDATE WBATTAGLNone199412151711NoneDOCUMENT NIT91 UPDATE WBATTAGLNone199412161613NoneEXPORT COVER NIT91 NIT91None199412190903NoneDOCUMENT NIT91 UPDATE WBATTAGLNone199412210856NoneDOCUMENT NIT91 UPDATE WBATTAGLNone199412211106NoneEXPORT COVER NIT91 NIT91None199412211115NoneDOCUMENT NIT91 UPDATE WBATTAGLNone199412301124NoneMNEGRI IMPORT COVER NIT91.E00 NIT91None199503081550NoneUnspecifiedNone199503081603NoneMNEGRI EXPORT COVER NIT91 NIT91.E00None199503092112NoneMNEGRI ARCSDTS NIT91 NIT91.TAR.GZ PREFNone199503092127NoneMNEGRI EXPORT COVER NIT91 /SCRATCH_AREA1/MNEGRI/NIT91.E00 NONENone199509191851NoneMNEGRI EXPORT COVER /DSDL1/CUSA/TILES/CUSA/NIT91 NIT91.E00None199606240930NoneMNEGRI EXPORT COVER /DSDL1/CUSA/TILES/CUSA/NIT91 NIT91.E00None199606251200NoneVectorPoint4787String11926GT-polygon composed of chains4788Albers Conical Equal Area29.545.5-96230.00.0coordinate pair1.01.0METERSUnknownClarke 18666378206.4294.98NIT91.PATpolygon attribute tableARC/INFO fileAREAArea of polygon in square coverage units (meters)ComputedPositive real numbersunspecifiedunspecifiedPERIMETERPerimeter of polygon in coverage units (meters)ComputedPositive real numbersunspecifiedunspecifiedNIT91#Internal feature numberComputedSequential unique positive integerunspecifiedunspecifiedNIT91-IDUser-assigned feature numberUser-definedIntegerunspecifiedunspecifiedFIPS5-digit County FIPS codeFederal Information Processing Standard01001 - 56998, none=0unspecifiedunspecifiedSTtwo-character state abbreviationU.S. Postal ServiceAL - WY, none = blankunspecifiedunspecifiedCNTYNAMECounty nameU.S. Geological Survey filesupper-case alphanumeric, none = blankunspecifiedunspecifiedPLYTYPEpolygon type: 0=county land, others are lakes, estuaries, etc.see narrative0-4,9unspecifiedunspecifiedWORKBvariable used for data processingn/aany integerunspecifiedunspecifiedAREA.ACREStotal county land area (all polygons) in acrescalculated from areas of polygons with like FIPS code and PLYTYPE=0numeric values greater than 0, missing = -99.00unspecifiedunspecifiedNTOT91total estimated nitrogen-fertilizer sales in tons, 1991U.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.0unspecifiedunspecifiedNTOT91.USErate of nitrogen-fertilizer use in county polygon in tons per square mileU.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.000unspecifiedunspecifiedK2O91estimated potash (K2O) sales in tons, 1991U.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.0unspecifiedunspecifiedK2O91.USErate of potash use in county polygon in tons per square mileU.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.000unspecifiedunspecifiedP2O591estimated phosphate (P2O5) sales in tons, 1991U.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.0unspecifiedunspecifiedP2O591.USErate of phosphate use in tons per square mileU.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.000unspecifiedunspecifiedAMNI91fertilizer sold as ammonium nitrate in tons, 1991U.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.0unspecifiedunspecifiedANHY91fertilizer sold as anhydrous ammonia in tons, 1991U.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.0unspecifiedunspecifiedNMIS91fertilizer sold as miscellaneous forms in tons, 1991U.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.0unspecifiedunspecifiedNSOL91fertilizer sold as nitrogen solutions in tons, 1991U.S. Environmental Protection Agency, 1990numeric values greater than 0, missing = -99.0unspecifiedunspecifiedUREA91fertilizer sold as urea in tons, 1991U.S. EPA, 1990numeric values greater than 0, missing = -99.0unspecifiedunspecifiedFIPSSTtwo-digit state FIPS codeFederal Information Processing Standard01 - 56, none = 0unspecifiedunspecifiedFIPSCNTYthree-digit county FIPS codeFederal Information Processing Standard001 - 998, none = 0unspecifiedunspecifiedNIT91.AATline attribute tableARC/INFO fileFNODE#Internal number of from-nodeComputedSequential unique positive integerunspecifiedunspecifiedTNODE#Internal number of to-nodeComputedSequential unique positive integerunspecifiedunspecifiedLPOLY#Internal number of polygon to left of arcComputedSequential unique positive integerunspecifiedunspecifiedRPOLY#Internal number of polygon to right of arcComputedSequential unique positive integerunspecifiedunspecifiedLENGTHLength of arc in coverage units (meters)ComputedPositive real numbersunspecifiedunspecifiedNIT91#Internal feature numberComputedSequential unique positive integerunspecifiedunspecifiedNIT91-IDUser-assigned feature numberUser-definedIntegerunspecifiedunspecifiedBNDTYPEboundary typesee narrative0-8unspecifiedunspecifiedNITROGEN-FERTILIZER SALES ATTRIBUTES
Nitrogen-fertilizer sales estimate were generated and are reported as
tons of actual nutrient. The data are summarized for fertilizer years
(i.e. the 1987 fertilizer year runs from July 1, 1986 to June 30, 1987).
Nitrogen-fertilizer sales estimates by county were constructed from
estimates reported by the U.S. Environmental Protection Agency (1990) for
1985-89 and by Jerald Fletcher (West Virginia University, written commun.,
1992) for 1990-91. The estimates are provided for seven years (1985-91)
in seven ARC/INFO coverages (NIT85, NIT86, NIT87, NIT88, NIT89, NIT90,
and NIT91); however, the 1987 Census of Agriculture data on fertilizer
expenditures used to disaggregate State sales totals to county-level
sales estimates represents only 1987 sales.
Eleven attributes were added to an ARC/INFO coverage for each year
of fertilizer-sales data. All attribute names contain a number that
represents the year of the data. For example, NTOT86 is the attribute
name for total nitrogen-fertilizer sales in 1986. Sales estimates are
provided for total nitrogen, potash, and phosphate, and for nitrogen
sold as ammonium nitrate, anhydrous ammonia, miscellaneous forms,
nitrogen solutions, and urea. Example nitrogen-fertilizer sales coverage
names, attribute names, and short attribute definitions are listed in
table 1.
Table 1. Nitrogen-fertilizer sales, 1991 coverage name, attribute names,
and short attribute descriptions
__________________________________________________________________________
NIT91--Coverage of nitrogen-fertilizer sales estimates, 1991
__________________________________________________________________________
Attribute name Description
__________________________________________________________________________
NTOT91 Total estimated nitrogen-fertilizer sales, 1991 (tons)
NTOT91.USE Rate of nitrogen-fertilizer use in county polygon (tons
per square mile)
K2091 Estimated potash sales, 1991 (tons)
K2091.USE Rate of potash use in county polygon (tons per square mile
P20591 Estimated phosphate sales, 1991 (tons)
P20591.USE Rate of phosphate use in county polygon (tons per square
mile)
AMNI91 Fertilizer sold as ammonium nitrate, 1991 (tons)
ANHY91 Fertilizer sold as anhydrous ammonia, 1991 (tons)
NMIS91 Fertilizer sold as miscellaneous forms, 1991 (tons)
NSOL91 Fertilizer sold as nitrogen solutions, 1991 (tons)
UREA91 Fertilizer sold as urea, 1991 (tons)
__________________________________________________________________________
Nitrogen-fertilizer sales estimates in counties represented by one
polygon are equal to county totals. For counties described by more than
one polygon, attribute values are provided for each polygon and are
calculated as the county total multiplied by the ratio of the area of
each county polygon divided by the total area of the county.
A missing-value code of -99.00 is used when no fertilizer-sales attribut
data are given for a county and for all nonland-area polygons. The
missing-value code can indicate any of the following conditions:
--fertilizer not sold in the county,
--crop data withheld because of census disclosure rules,
--crop data not available to the census, or
--crop data not published because county contains fewer than 10 farms.
COUNTY POLYGON ATTRIBUTES
Each county is identified by a five-digit Federal Information
Processing Standard (FIPS) code. The first two digits represent
the state and the three remaining represent the county within State.
County names (in upper case) and the two-character State
abbreviation also are included.
All polygons are coded by polygon type (PLYTYPE) as follows:
0 = U.S. land.
1 = Extensions of counties into the ocean and estuaries.
Some boundaries may be arbitrary.
2 = U.S. Great Lakes. Some boundaries between counties may
be arbitrary.
3 = Canadian Great Lakes.
4 = Canadian islands in Great Lakes, included for visual
cartographic purposes.
9 = External polygon.
All arcs are coded by boundary type (BNDTYPE) as follows:
0 = Coastline of United States.
1 = State-State border occurring on land.
2 = County-county border, within state, occurring on land.
3 = State-State border occurring on the ocean, an estuary,
or a Great Lake. Some of these borders are arbitrary.
4 = County-county border, with State, but occurring on the
ocean, an estuary, or a Great Lake. Some of these
borders are arbitrary.
5 = International border occurring on land.
6 = International border occurring on water.
7 = Canadian shoreline of the Great Lakes.
8 = Arbitrary separation line between the Canadian portions
of the Great Lakes.
9 = Closure line with the external polygon. This is
arbitrary.
All BNDTYPE values are determined from the adjoining polygons by
the routine, INDEX_COUNTY.AML. The coverage is indexed (ARC:
INDEXITEM) on FIPS code, State FIPS code, State abbreviation,
county name, polygon type, and boundary type.
Not AvailableU.S. Geological SurveyAsk USGS - Water Webserver Teammailing445 National CenterRestonVA201921-888-275-8747 (1-888-ASK-USGS)http://water.usgs.gov/user_feedback_form.htmlAlthough this data set has been used by the U.S. Geological
Survey, U.S. Department of the Interior, no warranty expressed or
implied is made by the U.S. Geological Survey as to the accuracy
of the data and related materials. The act of distribution shall not
constitute any such warranty, and no responsibility is assumed by
the U.S. Geological Survey in the use of this data, software, or
related materials.
Any use of trade, product, or firm names is for descriptive
purposes only and does not imply endorsement by the U.S.
Government.ExportFull coveragezipped1http://water.usgs.gov/GIS/dsdl/nit91.e00.gzSDTSFull coveragezipped1http://water.usgs.gov/GIS/dsdl/nit91.sdts.tgzNone. This dataset is provided by USGS as a public service.20041108U.S. Geological SurveyAsk USGS -- Water Webserver Teammailing445 National CenterRestonVA201921-888-275-8747 (1-888-ASK-USGS)http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+nit91FGDC Content Standards for Digital Geospatial MetadataFGDC-STD-001-1998